Application Analysis On Ultrasonic Resonator In Sensor Ranging

With the increase of large-scale construction engineering, the full load rate and busy work of tower cranes are more and more heavy. In order to prevent the major accidents of tower crane, such as collision and collapse etc in the course of using. By-developing an ultrasonic obstacle detection technique, is used in tower crane anti-collision system to ensure the tower crane safe operation. The problem of existing domestic ultrasonic obstacle detection technology is the short-distance detection, and is not suitable for tower crane anti-collision system. The technology for long-distance detection is in initial research stage.In long-distance ultrasonic detection, because of the air diffusion, absorption and other factors make acoustic signal produce great fluctuation with the change of distance. Besides the echo signal easily mixed with a large number of stray echo, and the system is difficult to effectively identify. So this paper designs a kind of ultrasonic resonator applied to long-distance ultrasonic obstacle detection technique, which aims to solve the problem of sound field fast attenuation and energy dispersive in long-distance ultrasonic detection system, and to realize the early-warning and obstacle avoidance.Firstly, according to mechanism analysis proves the ultrasonic resonator can improve the sound source with air field impedance matching effectively and radiant efficiency. The calculation model for ultrasonic resonator’s sound field directivity is derived by using Bessel function. The design parameters affecting the acoustic field directivity sharp degree is obtained, such as sound source frequency, opening size and resonator surface characteristics. Through Matlab simulation prove the correctness of theoretical analyses.Secondly, the ultrasonic resonator surface is designed. It need to determine the influence parameters about resonator surface. In the design, following two aspects of energy maximization and beam angle, and referring to the Matlab simulation results to calculate these design parameters.Then, the acoustic field is simulated by using ACTRAN software. For ultrasonic resonator’s sound field simulation is mainly refer to free field radiation mechanisms, that is the near-field basis for acoustical FEM and the far-field basis for acoustical IEM. Acoustic software use ACTRAN based on the technology for FEM and IEM. The different surface parameters and the different radiation distances in far-field are simulated, in order to get the sound field directivity diagram, radiation nephogram and optimize the design parameters. The results indicate that the change trend and the simulation results are the same as acoustic theory analysis.Finally, by using the ultrasonic obstacle detection trial system to collect echo signals. The amplified echo signals in "ultrasonic sensor-resonator" and "ultrasonic sensor-no resonator" are collected, compared and analyzed. Trial results show that the ultrasonic resonator which the thesis designs can effectively improve the detection distance.